Cranes or davits.



G. RENNERFELT & A. P. LUNDIN.

ORANES OR DAVITS.

APPLICATION FILED AUG. 24, 1908.

Patented Feb. 3, 1914.

6 SHEETSSHEBT 1.

WITNESSES G. RBNNERPELT & A. P. LUNDIN.

GRANES 0R. DAVITS.

APPLICATION FILED AUG. 24, 1908.

1,086,309. Patented b- 3.1914.

6 SHEETS-SHEET 2.

g IIVVENTORS G. RENNERFELT & A. P. LUNDIN.

CRANES 0R DAVITS. APPLICATION FILED AUG. 24, 1908.

1,086,309. Patented Feb. 3, 1914.

B SHEETSSHEET 3.

l a N WITNESSES //v EIVTORS G. RENNERFELT & A. P. LUNDIN.

GRANES OR DAVITS. APPLICATION FILED AUG. 24, 1906 Patented Feb. 3, 1914.

6 SHEETS-SHEET 4.

l/VVEN OHS G. RBNNERFELT S; A. P. LUNDIN ORANES 0R DAVITS.

- APPLICATION FILED AUG. 24, 1908 4 I 1 086,309 Patented Feb. 3, 1914.

v 6 SHEETS-SHEET 5.

a u 4 J0 d a Z S f a a i L a I M z a G. RBNNERFELT & A. P. LUNDIN.

GRANBS OR- DAVI TS.

APPLICATION FILED AUG. 24, 1908 Patented Feb. 3, 1914.

6 SHEETS-SHEET 6.

0044.. frfcZ. m

' GUSTAF RENNERFELT AND ANDREAS P. LUNDIN, OF NEW YORK, N. Y.,ASSIGNORS, BY

MESNE ASSIGNMENTS, TO ASTOR TRUST COMPANY, TRUSTEE, A CORPORATION OF NEWYORK.

CRANE-S on navrrs.

Specification of Letters Patent.

Patented Feb. 3,191s.

4 Application filed August 24, 1908. Serial No. 449,969.

To all whom it may concern Be it known that we, GUsTAr RENNERFELT andANDREAS P. LUNDIN, the said RENNER- FELT a subject of the King of Swedenand the said LUNDIN a citizen of the United States,

both being residents of the borough of Mansiderable weight which it maybe desired, not only to-swing over. one side of a vessel,

but also to swing from one side to the other. Obviously, however, ourinvention may be utilized in either land. or marine work whereversimilar conditions exist or wherever it is deslred to accomplish theresultswhich can be accomplished by the use of this invention. 7

Broadly speaking, our invention may be useful under any circumstanceswhere it is desired to handle loads of appreciably different weights orloads of considerable weight, to move a load from one point to a point aconsiderable distance away where it is necessary to raise and lower thesame, or to pick up any one of a number of devices covering aconsiderable space and move them readily to another position.

In the accompanying drawings, we have shown the preferred form of ourinvention as we prefer to apply it to a war ship. In these drawings,similar reference characters designate corresponding parts.

Figure I is a plan view of a war ship, partially diagrammatic,illustrating one method of arranging ourdavits and intended primarily toindicate one set of conditions under which our invention would bepeculiarly useful; Fig. II is an end elevation showing one davit and itsmethod of operation; Fig. III is a side elevation of the sameconstruction; Fig. IV is a detailed viewof our preferred construction ofthe worm, nut and supporting and connecting parts for this construction;Fig. V is a more detailed view,

partlyin longitudinal section, illustrating the bearing for the worm;Fig. VI is a transverse sectional view through the line VI-VI, Fig. V;Fig. VII is a side view, partially in section, showing our preferredmethod of securing the boom to the davit arms, and

also our preferred method of securing other parts to the beam and davitarms; Fig.VIII is an end view ofthe construction illustrated in Fig.VII; Fig. IX is aside View, partially in vertical cross-section .of adavit arm and support therefor; Fig. X isa plan view of the form ofdavit supporting rack illustrated in Fig. IX; and Fig. XI is adiagrammatic view illustrating our preferred method of wiring andelectric control of our preferred construction. Fig. XII is a detailview.

Referring now to Fig. I, it will be noted that we have shown on eachside of a war ship eight boats running from forty-foot steam cutters of18,700 pounds down to 7:,

small dinghies. 'In practice, in view of the weight of these boats, theextent of space covered by them, so far as-their length is concerned andwhen arranged end to end,

and in View of the construction of the presout day war ship and thearrangement of the boats carried by it, we prefer, in this particularembodiment, to employ two sets of davits, each set embodying ourimprovenected by a boom, and each davit embodying certain other of ourimprovements.

In Fig. I, we have diagrammatically indicated the location of the davitswhich are invments, each set comprising two davits con- 35 dicated inthat figure, A, and the connecting Turning now to a description of thedavit, a 100 designates the davit arm proper, provided at its lower endwith a segment a shown as providedwith teeth a As shown, the davit A ispivoted at a to a nut D which, as will hereinafter be more fullydescribed, travels 5 on a worm O.

Turning for a moment to Figs. IX and X,

E designates a rack suitably secured to the deck in any suitable mannerand provided,

as shown, with two sets of teeth 6? e separated by a space e. In Fig.IX, the upper surface of the teeth is indicated by the dotted line. Asshown, again in Fig. IX, our preferred form, the lower segment a of thedavit is supplied with two sets of teeth a a arranged on each side of atrack a, which track projects down through the space a between the teethof the rack and rests upon the upper surface e of the central portion 6of the casting of the rack. It will be further noticedby referring toFigs. IX and X that the segment in addition to its intermediate track ais provided with two outside tracksengaging with similar outside tracksarranged on the rack. Furthermore, whereas the intermediate track arolls along the normal plane of the casting or in other words, along theupper surface of the central portion 6 of the rack, the outside tracksof the rack are raised and the outside tracks of'the .segment areshortened. This may be said to result in raising the pitch line. Inother words, as shown, whereas the intermediate track (1- ex tends tothe bottom of the'teeth e e the outside tracks of the segment arerolling along the plane, which substantially bisects the pitch of theseteeth 6 (2 Still referring to Fig. IX, 4 designates the frame propershown in cross-section,-D the traveling nut, Do a threaded hole thereinto permit the insertion of the worm on which the nut travels, and F aguide-plate secured at each end to the frame and adapted to guide thetraveling nut laterally and at the same time to permit of sufficientplay vertically. The.

rack and frame are preferably rigidly joined together in any suitablemanner. The rack and frame may be cast integral as shown or separatelyand then bolted together, or both of the same may be bolted to the floorby the same bolts, thus securing the two parts to the floor or deck andalso to each other.

Turning back to Fig. II, it will be seen that when the worm C is rotatedin any manner, the traveling nut D will inevitably move along the same,outward or inward, depending upon the direction of' rotation of theworm, and the davit will also be caused to swing around its pivot a onaccount of the,engagement of the teeth a on its seg menta with the teeth(3 of the rack E, the track a rolling between the teeth 6 and upon theupper surface 6 of the casting E, producing great stability and evennessof movement.

Referring to Figs. II, V and VI, Q designates trunnions or, a trunnionmounting for the bearing V for the worm C. Figs. V and VI show thepreferred construction of this hearing. 12 designates a casing, throughwhich the outer end of the worm passes.

Arranged within the casing is an antithrust device W, comprising rollersW. o is a combined cover and bearing suitably, secured to the casing asby bolts and. nuts. As shown, the rollers W are provided with sphericalfaces and anti-thrust blocks Y, Y are arranged on each side of theserollers to permit the faces thereof to come into contact therewith. Anysuitable means of securing and offering proper resistance to theseanti-thrust devices Y and Y may be employed. As shown, the anti-thrustblock Y abuts against a turned-in portion of the casting of the casingand the anti-thrust block Y against the combined bearing block and cover4). It is our intent that when the devices are running normally andwithout any undue pressure in any direction, the rollers shall havefreedom of movement. thrust comes in either direction, the rollers Wwill be forced hard against one of the anti-thrustdevices Yor Y, thustaking up the end thrust in that direction.

Referring now to Figs. XI and XILT is a brass drum keyedto a shaft P butinsulated therefrom. Keyed to-this same shaft P is a worm wheel 39,which is engaged by a worm 0 on the davit worm shaft C. As indicated inFig. IV, the pitch of the worm c is very muchfiner than that of the mainworm O. For example, in actual practice, on the main worm we have used apitch of from three-quarters of an inch up, depending upon theconditions to be met. A pitch of one-eighth of an inch will probablysuffice for the auxiliary worm 0. Consequently, as the main shaftrevolves in a positive direcition, it will drive its metallic drum inone .direction and when the main shaft is rever'sed, it will drive themetallic drum in the reverse direction. As shown, particularly in Fig.XI, each metallic drum is provided with two pieces of insulatingmaterial t t respectively. As' will be ointed out more fully hereinafterin describlng the electric connections, the main drum shaft, the worm C,the auxiliary worm 0 and the respective pitches ofthese worms, and alsothe number of teeth in the worm wheel will be proportioned and arrangedso that when the davit arm reaches its. extreme position in onedirection, the insulating piece 25 will reach a point directly beneaththat brush contact between which and the metallic surface of the drumhas closed the armature switch controlling the motion of the davit inthat direction; and when the davit reaches its extreme position in theopposite direction, the insulating piece t will reach a point directlybeneath the other brush which in a similar way controls the motionof thedavit in that direction.

It will be obvious from a study of Fig. II that when the davit A has theupper end of its davit arm proper (L directly above posi- If an end tion3, it will be closer to the deck than when in its intermediate position.or over the boats marked 1 and 2, and also that by merely stopping thedavit at the proper moment, the ropes connected thereto can be made todrop perpendicularly over any desired point of the total scope ofmovement of the outer end of the davit arm. Obviously, as the distancefrom the top of the davit arm to each boat when on the deck will alwaysbe different, it p is necessary to have some contrivanceto permit ofvarying the length of the'rope. Furthermore, as the boats on a ship maybe a considerable distance from the water, it will be necessary, afterthe same has been raised and. swung outboard by the movement of davit,to lower the same and to rehoist the same. Consequently, we haveprovided what we shall call a hoisting drum adapted to be operatedindependently of the worm which controls the movement of the davit, andwhich will not only permit the movement of lowering and hoisting to anyextent desired, but will also permit of the length of the ropeintermediate the upper end of the davit arm proper and the object to belifted to be altered at will. a

Referring to Fig. III, B designates a boom connecting the upper or outerends of the davit arms proper a a. This boom may be secured to the davitarm in any suitable manner, but we have indicated' our preferred methodof securing it in Figs. VII

and VIII, where we have shown in the upper end of each davit arm a a, apocket a The davit arms are preferably hollow castings, as shown. Theends 6 of the boom, which is also preferably hollow, pass throughapertures in the wall of the casting of the davit arms and into-thepocket 0..

6 indicates a fastening bolt passing down through the upper and lowerwalls of the pocket a and also through an aperture in the end I) of theboom. 6 and b are nuts or a head and nut for securing and maintainingthe parts in operative -position. Secured to each boom at its lowersurface in any suitable manner are two or more pul-' pulleys should besecured to the boom in 55' most. instances, Under any conditions whereboats of varying lengths-are to be raised and lowered, or where for anyother reason it will be unsatisfactory to have a constant distancebetween two pulleys, the

pulleys may be adjustable longitudinally with regard to the boom, or, asshown, and as preferred for this class of work, two: or more sets ofpulleys will be secured to the ,boom. For example, as illustrated inFigs? III and VII, we have shown two sets of davit comes over andprevent' the possibility of the ropes fouling or being forced ofi' thesheaves.

Where two or more sets of 1 pulleys are used, it .is preferable to haveU I I,

the upper rop'es running over the sameg' wound around separate hoistingdrums.

The hoisting drums for each davit may be actuated each by its own motor,or, preferably alternately by the same motor. Where we only have twosets of pulleys, as shown in Fig. III, we have, as shown, two holstingdrums H H which will bealternately actuated by a common motor. Any wellknown means of throwing the motor into gear with first one drum and thenanother "may be utilized.

As shown in Figs. II, III, VII and VIII, the ropes in passing from thewinding drum to the boat or other object to be lifted are I each securedat one end to their respective winding drums, thence pass upward overwhat we shall call a guiding sheaveor pulley J, thence around theirrespective pulleys F F down around an attaching pulley K K and back. toa suitable point of attachment on their respective pulleysF F The numberof sets of pulleys F F will determine the number of hoisting drums andalso the number of guiding pulleys J Each hoisting rope shouldpreferably have its independent guidin pulley, and, as illustrated inFig. VII this may be accomplished by using what is'known as a doublesheave j 7' or by using a plurality of separate sheaves for thispurpose. The same is true of the lower guiding pulley or pulleys J whichmay be secured to the frame or deck in any suitable manner and ,7 at anypoint intermediate the drum and upends of the structure. We prefer tohave our davits start simultaneously and move at the same rate of speedand stop simultaneously. It is also" important that each davit shouldhave a definite limit of movement inv either direction. In other words,if

for any reason one davit should get somewhat. ahead of the other duringthe course 'of movement of the entire structure it is esscntial thateach davit at the end of its movement should be in the same position asthe other. li o will describe later how by the preferred system ofwiring and electrical connections we arrange to have our principalmotors mechanically independent of each other, started simultaneously,driven at approximately equal speed and yet auto matically stopped, eachat its extreme position, independently of what may be the position oftheother davit. When we come to the hoisting drums and the hoisting motorsm m we have a diiierent set of conditions and ditlerent results to bedesired. Here again we desire to have the hoisting motors connected withand operated by the same circuit, but we desire to be able to vary thespeed of both these motors m m at will and finally to be able to varythe speed of: one thereof without changing that of the other. One end ofa boat, for example, may be very much heavier than another. in thiscase, the heavier end of the boat will put a greater strain on the ropesupporting that end, re sulting in a distinct stretching of the rope andadditional lowering of that end of the boat. Consequently, if the boatis being lowered the motor controlling the hoisting drum at that endshould be slowed down until the other end reaches the same level, or thespeed of the'hoisting drum at the higher end of the boat should beaccelerated. in raising under similar conditions, the process wouldobviously be reversed.

Turning now to Fig. Xl, which is a diagrammatic view of our preferredmethod of wiring, we will first take up the circuit which controls themain motors M hil 10 and 11 designate respective positive and negativewires leading to a suitable source of supply. 100 designates the mainswitch which may be located at any suitable point. in tracing thecircuits, we shall assume" in future that this switch is closed.Starting with the positive wire 10 current passes through switch 100,through the line 12, thence through the line 14, thence up the line 16through the solenoid SS102, thence up the line 18 to the starting switch10 which is shown as being in contact for the positive rotation or theworm. From this starting switch 104 the current passes through the line20, thence to the line 22, and thence right and left through the lines24 and 26 respectively, and thence through the solenoids S8106 andSSlOS, thence up through the lines 28 and 30 respectively into thebrushes 32 and 3a respectively, through the metal drums T T and upthrough the other brushes 51 and 53 respectively to, the common line 29,down through the line 27 to the junction point 25, thence through theline 23 to the line 21, 17 to the junction point 15, down through theline 13 andacross the negative side 101 of the main switch, and back tothe main negative line 11. It will be noted that the current. in passingthrough this circuit has first energized the solenoid S8102 therebyclosing its switch 4:00, and second has also energized the solenoidsS8106 and S8108 thereby closing their respective switches 114i and 116.

The result of this first action in closing the ,solenoid switch 400 isto complete the shunt field, the circuit being from the positive line 10across the positive side of the main switch 100 through the wire 12,thence through the wires 1a and 10 across the solenoid switch 400,through the line 36, through the shunt field 38 to the negative side ofthe shunt field 19, back through. the lines 17, 15 and 13 to thenegative side of the main switch 101 and back to the main negative linell. The second action in closing the solenoid switches 114 and 116results in sending a current through the armatur'es of the main motors MM respectively and in a positive direction or from the'positive to thenegative line. These solenoid switches 114 and 116 closed, the currentstarts with the positive main line 10 across the switch 100, up the line40 through the starting resistance R andthe solenoid 500, line 12, tothe junction point t, through the line at) to the junction point 18,thence right and left through the solenoid switches 11% and 116respectively and through tie armatures of the motors M, through thelines 50 and 52, and back through the lower 'hranch oi the switches 11%and 110 to the line 53, thence down through junction point 15 and line13 to the negative side of the main switch and t irough the negativeside oi the main switch 101 to the negative main line 11.. if thestarting switch 104 is thrown in contact with the other contact point105, the solenoids S'SllO and 12 will be energized in stead of thesolencir 1.06 and 5553108, thus reversing the direction of the currentthrough the main armature of the main motors M M and thus reversing thedirection of the said motors and consequently the direction of rotationof the worm.

We have already described the construction and operation of the metallicdrums T T and stated that each had arranged in its periphery two piecesof insulating material If and 23 respectively. The brushes 31 and 83leading back to the negative line are always in contact with themetallic surface of the drum. The moment the positive brushes 82 or 34strike the insulating strips 3 t, the armature circuit is broken forthat motor and the motor will consequently stop. The same statement istrue with regard to the reverse brushes 51 and 53 and the insulatingstrips 6 In other words, these insulating strips are so arranged on themetallic drums T that when the davit reaches its extreme position ineither direction the brush which must be in contact with the metallicsurface ofand 14: to the junction point '306, through the drum tomaintain the circuit will strike the insulating material, thus breakingthe circuit which controls the armature switches, thus allowing them todrop and shut ofi power and prevent any further movement of the motor.Consequently, under normal conditions both main motors willv startsimultaneously, will roceed at substantially the same speed, an normallywill come to a stop approximately simultaneously.

Turning now to the motors for the hoist ing drums, we find themdesignated m m} in Fig. XI. Here we have again a starting switchdesignated 200:. As indicated in the drawing, to hoist, the switch isthrown into contact with point 201, and, to lower, with point 202.Taking up the hoisting operation first, the current again passes frompositive line 10 across the main switch 100, through lines 12, 1 1 and16, thence line 218 and through the solenoid S3220, through line 222,through the starting switch 200, line 22 1, to the solenoids SS226 andSS228, through line,230 down to the junction point 225, through the line223, junction point 221, through lines 219 and 217 back to the line 13across the negative side of the main switch 101 back to the mainnegative line 11. By closing this circuit, two results have beenproduced. In the first place, the solenoid switch 220 has been closed,and in the second place, the two solenoid switches 236 and 238 have beenclosed. The first act of closing the solenoid switch 220 produces twoseparate results. In the first place, it connects up the rheostat 200",and in the second place, it completes the shunt fields SF 215 and 240.The second action of closing the solenoid switches 236 and 238 throwsthe current through the armatures of the hoisting motors m mrespectively.

An inspection of the illustration of the switch 200 will show that thereis a piece of insulation 200 intermediate the point of connection ofthe. positive line 222 and the lower end of the switch, which lower end200 will always be in contact first with a short segment 300 and secondwith a longer segment 301. So long as the solenoid switch 220 isdenergized no circuit will be closed as a result of the contact betweenthe segments 300 and 301, formed by the bar 200 So soon as the solenoidswitch 220 is closed, however, the current will pass across the mainswitch 100, through the lines 12, 1 1, 16, 218 and 302, through the longsegment 301 across the bar 200 through the segment 300, through the line304, through the shunt fields SF215 and 240 down to the line 223 backthrough the lines 221, 219 and 217 across the negative side of theswitch 101 and back to the main negative line 11. Furthermore, thecurrent will pass across the main switch through the positive lines 12the starting resistance R through the solenoid 500, .line 308, past thejunction point 309 through the line 310, through the lines 312 and 31 1,across the solenoid switches 238 and 236, through the armatures ofthehoisting motors m m, back through the lower branches of the solenoidswitches 238 'and 236, through the lines 313 and 311 to the junctionpoint 221, and thence backv to the negative main line 11. If the switch200 is thrown into contact with the lower contact point 202, thesolenoids S8240 and SS212 will be energized and the directionofthecurrent reversedthus reversing the direction of the motors andhoisting drums.

- Returning again for a moment to the segments 300 and 301 and theconnecting bar 200 we have here a rheostat which will permit of avariation of the amount of resist-- ance thrown into the shunt fieldcircuit, or in other words which will determine the potentiality of thecurrent thrown over the shunt field, thus permitting an increase in thespeed of both the hoisting motors. 4,00 designates another switch whichmay be closed to weaken the shunt field of one of the motors only. Forexample, when this switch 400 is closed, the shunt current will passthrough the shunt field SF215 of the hoisting motor m and to thejunction point 246 where it will divide,-part going through the shuntfield 240 and directly down to the negativ line 223 and the rest up theline 402 to the switch 400, down through the line 404, through theresistance R and thence through theline 406 back to the negative line223. The addition of this resistance R will increase the speed of thearmature of the motor m thus creating a variance in s eed between thetwo hoisting motors and oisting drums. This additional resistance shouldbe applied to the slower of the two motors which can be tested outbefore attachment to find out which is the slower under a given current.

Referring now to the starting resistances R R (Fig. XI), each is shownas of the same construction. Any form of resistance device which, afterthe circuit through the armature has been closed, will automatically cutout the resistance may be employed.

In Fig. XI, R designates the starting resistance in its startingposition. R designates the same with the resistance cut out. So long asthe main circuit through the armature in either case is closed, thesolenoid 500 becomes energized, draws up the iron core 501 changing thecontact point from the position shown at R to that shown at R. 502designates a dashpot in order to insure a gradual upward movement andconsequent gradual cutting out of the resistance.

Having. described our invention, what we claim and desire to secure byLetters Patent, is

' 1. The combination of a davit, a track to support it, a nutmountedpivotally in the' davit, a frame joined with the track, a casing mountedon trunnions in the frame, a worm-shaft projecting with both endsthrough the casing and threaded into the nut, an end-thrust bearing anda radial bearing for the worm, both said bearings being contained withinthe casing, and means for rotating the worm.

2. The combination of a davit, a track to support it, a nut mountedpivotally in the davit, a frame, a bar above the nut fastened to theframe and arranged to be in contact with the nut latp 'ally but notvertically, a casing mounted on trunnions in the frame, a worm shaftprojecting with both ends through the casing and threaded into the nut,a thrust bearing and a radialbearin'g for the worm',-both of saidbearings bemg contained within the casing, and means for rotating theworm.

3. The combination of two davits ar-- ranged to move in a verticalplane,each davit having a pocket at its top, a boom having endsmounted in saidpockets, a bolt secured in a vertical direction through the top of eachdavit and through each end of the boom. I

4. The combination of two davits arranged to move in a vertical plane,each davit having a pocket'at its top, a boom having its ends mounted insaid pockets, a bolt secured in vertical direction through the top ofeach davit and through each end of the boom, means mechanicallyindependent of each other for imparting mot-ion to the davits atapproximately equal speeds, and electrormagnetically operated automaticmeans for stopping each davit at its extreme position in each direction.

5. The combination of two davits, two electric motors mechanicallyindependent of each other, and arranged each one to move a davit in avertical plane, a starting resistance in common for both motors, anoperating switch and electro-magnetic means'for closing simultaneouslythe field circuits of both the motors and for starting or revers ingboth of the motors and electro-magnetically operated means forautomatically stopping one davit at each of its extreme positionsindependently of the position of the other davit.

6. The combination with a pair of davits for handling a boat, of twomotors arranged each one for moving a davit in a vertical plane, a boomloosely bolted to the tops of both davits, a .sheave suspended from theboom, a rope arranged to run over the sheave and'to be connected to theboat, a motor and connection between the motor and the rope, anoperating switch and electrofor handling a boat, of two motors arrangedeach one for moving a davit in a vertical plane, a boom loosely boltedto the tops of both davits, two sheaves suspended from lugs rigidlysecured to the boom, a rope arranged to run over the said sheaves and tobe connected to the boat, a motor and connection between the motor andthe rdpe, an operating switch and electro-m-agnetic means for startingsimultaneously both of said first motors, automatic means for stoppingone of said motors at each of its extreme positions, and an operating.switch for controlling the speed of the latter motor.

8. A pair of electrically operated davits for manipulating a boat,comprising two independent electric motors for moving the davits in avertical plane, an operating switch having an open, a forward, and areverse position, electro-magnetic means actuated through said operatingswitch for controllingthe movement of said motors, auto maticelectromagnetic means for stopping one d'avit at its extreme positionindependently of the position of the other davit, pulleys and sheavesconnected with the davits, ropes arranged to be fastened to the boat andguided by the pulleys, two independent electric motors, connectionbetween the motors and the ropes, and means for controlling the speed ofsaid latter two motors.

9. In apparatus for manipulating life boats, the combination or twodavits, an electric motor arranged to cause movement in a vertical planeof one davit independently of the other davit, an operating switch andelectro-magnetic apparatus for controlling said movement of both davits,automatic electro-magnetic apparatus for stopping said movement ofeither one of said davits at its extreme position independently of theposition of the other davit, pulleys, ropes guided by pulleys andarranged to be fastened to the life boat, and means for winding therope.

10. The combination of two davits for manipulating a life boat, a boombolted loosely to the topsof both davits, so as to join the davits andto permit relative variation in their movement in a vertical plane, anindependent motor and mechanism for moving each davit in a verticalplane, means for controlling the speed of said motors, sheaves andulleys fastened to the davits and to the com, ropes guided by saidsheaves and pulleys and arranged to be fastened to the life boat; twomotors arran ed to wind the ropes, means for controlling and varying thespeeds of said latter motors, and means for varying the speed of one ofsaid latter motors independently of the speed of the other motor.

11. The combination of a davit arranged to move in a vertical plane, aframe therefor, a nut mounted pivotally in the davit, a bearing mountedpivotally in the frame, a worm shaft journaled in the bearing andthreaded in the nut, means for rotating the worm shaft, and means forsustaining end thrust from the worm shaft.

12. In a vertically swinging davit, the combination with a rack providedwith two sets of teeth separated by a space, of two tracks arrangedrespectively on the outside of each set of teeth and having their pitchline raised above that of the rack, a segment provided at the lower endof the davit and having two sets of teeth adapted respectively to engagewith the teeth on the rack, an intermediate track on the segment andarranged between its two sets of teeth and adapted to project downthrough the space between the two sets of teeth on the rack, and twooutside tracks arranged on the segment and adapted to engage with theoutside tracks on the rack.

13. The combination of two davits arranged to move in a vertical plane,and on each side of another vertical plane at right angles thereto andintersecting the base, a boom connecting the upper ends of said davits,means for imparting motion to said davits in opposite directions,pulleys secured to said boom, a device to be manipulated by said davits,ropes running through said davits and connected to said device, andmeans for insuring the clearing of the ropes from said boom as thedavits and boom swing across said vertical plane extending upwardbetween and from the base of said davits.

14:. The combination of a davit arranged to move in a vertical plane, aframe therefor, a worm shaft journaled at one end in a suitable bearingin the frame and free at its other end, a nut carried by the davit andthreaded on the worm, and means for sustaining end thrust from the Worm.

15. The combination of a davit arranged to move in a vertical plane, aframe therefor, a worm shaft for moving said davit journaled at one endof said frame, anut mounted pivotally in the davit and threaded on theworm, and means for sustaining thrusts from the Worm comprising a casingpivotally mounted in the frame and antithrust devices contained withinthe casing.

In witness whereof, we have hereunto subscribed our names in thepresence of two subscribing witnesses.

GUSTAF RENNERFELT. ANDREA-S P. LUNDIN.

Witnesses:

Jos. F. OBRIEN, Rosa V. FINN.

